\begin{table}[ht] \centering
\newcolumntype{R}{>{\raggedleft\arraybackslash}X}
\newcolumntype{L}{>{\raggedright\arraybackslash}X}
\newcolumntype{C}{>{\centering\arraybackslash}X}

\caption{Test}
\label{tab:abi_denv}
{\scriptsize
\begin{tabularx}{\raggedleft}{@{}lCCCC@{}}

\toprule
&{(1)}&{(2)}&{(3)}&{(4)} \tabularnewline \midrule
{}&{}&{}&{}&{} \tabularnewline
\midrule \addlinespace[\belowrulesep]
Age enrollment 20--25 Months Mean&0.214&0.988&1.029&0.943 \tabularnewline
Age enrollment 9--15 Months Mean&0.225&0.975&0.940&0.862 \tabularnewline
P-value&\textbf\{(0.024)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\} \tabularnewline
N&6649.000&1.3e+04&1.3e+04&1.3e+04 \tabularnewline
Age enrollment 15--20 Months Mean&0.227&0.982&1.011&0.906 \tabularnewline
Age enrollment 9--15 Months Mean&0.225&0.975&0.940&0.862 \tabularnewline
P-value&(0.665)&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\} \tabularnewline
N&7266.000&1.4e+04&1.4e+04&1.4e+04 \tabularnewline
Age enrollment 20--25 Months Mean&0.214&0.988&1.029&0.943 \tabularnewline
Age enrollment 15--20 Months Mean&0.227&0.982&1.011&0.906 \tabularnewline
P-value&\textbf\{(0.006)\}&\textbf\{(0.000)\}&\textbf\{(0.049)\}&\textbf\{(0.000)\} \tabularnewline
N&6513.000&1.2e+04&1.2e+04&1.2e+04 \tabularnewline
\bottomrule \addlinespace[\belowrulesep]

\end{tabularx}
\\ \parbox{\raggedleft}{\scriptsize Note:}
}
\end{table}
